Revolution counters that make available a steering angle datum of a vehicle are known in the existing art, in which context an actual measuring element can measure only up to a maximum of 360°. Measurements up to 360°/n, where n is a natural number, are also known. Half-revolutions of 180° can in particular also be counted, for example in the context of giant magnetoresistance (GMR). The steering angle is thus no longer unequivocal for steering angles above 360° (several revolutions).
Also known are revolution counters that are embodied in noncontact fashion and are functional even at zero current (e.g. when the ignition is switched off or the motor vehicle's battery is disconnected). In this connection, German Published Patent Appln. No. 10 2004 020 149 discloses a sensor element for a revolution counter, which element has a layered structure that uses the GMR effect to read out revolution information. The revolution counter is thereby capable, without an energy supply, of bringing about a change in magnetization in the sensor element when a magnetic field is moved past the sensor element.
In addition, an unequivocal representation of steering angles greater than 360° conventionally requires two gears having integrated magnets, a magnetic field vector being evaluated by a magnetic field sensor element, and the steering angle being calculated via a vernier algorithm.